NFS: Count the bytes of skipped subrequests in nfs_lock_and_join_requests()

trondmypd · trondmypd · commit 1bd5d6d08ea7 · 2017-09-09T16:43:09.000-04:00
If we skip a subrequest due to a zero refcount, we should still count
the byte range that it covered so that we accurately reconstruct the
original request size.

Signed-off-by: Trond Myklebust &lt;trond.myklebust@primarydata.com&gt;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
@@ -504,8 +504,12 @@ nfs_lock_and_join_requests(struct page *page)
 	for (subreq = head->wb_this_page; subreq != head;
 			subreq = subreq->wb_this_page) {
 
-		if (!kref_get_unless_zero(&subreq->wb_kref))
+		if (!kref_get_unless_zero(&subreq->wb_kref)) {
+			if (subreq->wb_offset == head->wb_offset + total_bytes)
+				total_bytes += subreq->wb_bytes;
 			continue;
+		}
+
 		while (!nfs_lock_request(subreq)) {
 			/*
 			 * Unlock page to allow nfs_page_group_sync_on_bit()
